Internal combustion engines generate exhaust as a by-product of fuel combustion within the engines. Engine exhaust contains, among other things, unburnt fuel, particulate matter such as soot, and harmful gases such as carbon monoxide or nitrous oxide. To comply with regulatory emissions control requirements, engine exhaust must be cleaned before it is discharged into the atmosphere.
Engines typically include an after-treatment device that removes or reduces harmful gases and particulate matter in the exhaust. The after-treatment device contains components such as oxidation catalysts and soot filters to help clean the exhaust gases. The presence of these components, however, can create increased resistance to the flow of exhaust (back pressure) from the engine through the exhaust system. Space constraints in engine applications can further compound these back pressure problems because the exhaust flow may have to encounter sharp turns as it passes through the after-treatment device. The geometry and size of exhaust flow passageways, and the location and arrangement of the catalysts and filters in the after-treatment systems can significantly influence back pressure.
An exemplary after-treatment system is disclosed in World Intellectual Property Organization International Publication No. WO 2011/087819 of Kiran et al. that was published on Jul. 21, 2011 (“the '819 publication”). Specifically, the '819 publication discloses a transition section for turning the flow exiting a turbocharger into three inputs of the after-treatment system. The '819 publication also discloses using restriction plates with openings having different apertures to control the amount of exhaust entering each of the three after-treatment system legs.
Although the system of the '819 publication may be adequate for situations with a relatively small number of after-treatment legs, it may not be suitable for engine applications with a large number of after-treatment components necessary to comply with modern emissions control requirements. Further, space constraints in certain engine applications may make it difficult to include an additional transition section for turning the flow as disclosed in the '819 publication. Moreover, although using openings of different sizes may help to distribute flow into different after-treatment legs, these restriction plates may also add resistance to the flow of exhaust. Notably, the '819 publication focuses on distributing the flow uniformly to more than one after-treatment leg but does not disclose a way to reduce back pressure in the after-treatment system.
The after-treatment device of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.